This invention relates to telemetry and in particular to analogue telemetry systems and methods for concatenated optical amplifier systems.
Optical amplifiers such as those based on specially doped fibres or semiconductor materials are likely to be employed in future long haul optical fibre cable transmission routes since they can provide considerable enhancement thereto. They will be able to directly to amplify the optical signal and therefore simplify the intermediate repeater stages by eliminating the need to perform full 3R (re-shaping, re-timing, re-generation) signal transmission. A system including a plurality of optical amplifiers should have some facility for diagnosing where a fault has occurred and referring this information to one of the terminal stations of the system.